﻿using System;
using System.Collections.Generic;
using System.Text;
using System.Security.Cryptography;
using System.IO;

namespace Framework.Utility.Extensions
{
    /// <summary>
    /// 异常处理类
    /// </summary>
    public class CryptoHelpException : ApplicationException
    {
        public CryptoHelpException(string msg) : base(msg) { }
    }

    /// <summary>
    /// CryptHelp 文件加密/解密
    /// </summary>
    public class DESFileClass
    {
        private const ulong FC_TAG = 0xFC010203040506CF;

        private const int BUFFER_SIZE = 128 * 1024;

        /// <summary>
        /// 检验两个Byte数组是否相同
        /// </summary>
        /// <param name="b1">Byte数组</param>
        /// <param name="b2">Byte数组</param>
        /// <returns>true－相等</returns>
        private static bool CheckByteArrays(byte[] b1, byte[] b2)
        {
            if (b1.Length == b2.Length)
            {
                for (int i = 0; i < b1.Length; ++i)
                {
                    if (b1[i] != b2[i])
                        return false;
                }
                return true;
            }
            return false;
        }

        /// <summary>
        /// 创建DebugLZQ ,http://www.cnblogs.com/DebugLZQ
        /// </summary>
        /// <param name="password">密码</param>
        /// <param name="salt"></param>
        /// <returns>加密对象</returns>
        private static SymmetricAlgorithm CreateRijndael(string password, byte[] salt)
        {
            PasswordDeriveBytes pdb = new PasswordDeriveBytes(password, salt, "SHA256", 1000);

            SymmetricAlgorithm sma = Rijndael.Create();
            sma.KeySize = 256;
            sma.Key = pdb.GetBytes(32);
            sma.Padding = PaddingMode.PKCS7;
            return sma;
        }

        /// <summary>
        /// 加密文件随机数生成
        /// </summary>
        private static RandomNumberGenerator rand = new RNGCryptoServiceProvider();

        /// <summary>
        /// 生成指定长度的随机Byte数组
        /// </summary>
        /// <param name="count">Byte数组长度</param>
        /// <returns>随机Byte数组</returns>
        private static byte[] GenerateRandomBytes(int count)
        {
            byte[] bytes = new byte[count];
            rand.GetBytes(bytes);
            return bytes;
        }

        /// <summary>
        /// 加密文件
        /// </summary>
        /// <param name="inFile">待加密文件</param>
        /// <param name="outFile">加密后输入文件</param>
        /// <param name="password">加密密码</param>
        public static void EncryptFile(string inFile, string outFile, string password)
        {
            using (FileStream fin = File.OpenRead(inFile), fout = File.OpenWrite(outFile))
            {
                long lSize = fin.Length; // 输入文件长度
                int size = (int)lSize;
                byte[] bytes = new byte[BUFFER_SIZE]; // 缓存
                int read = -1; // 输入文件读取数量
                int value = 0;

                // 获取IV和salt
                byte[] IV = GenerateRandomBytes(16);
                byte[] salt = GenerateRandomBytes(16);

                // 创建加密对象
                SymmetricAlgorithm sma = DESFileClass.CreateRijndael(password, salt);
                sma.IV = IV;

                // 在输出文件开始部分写入IV和salt
                fout.Write(IV, 0, IV.Length);
                fout.Write(salt, 0, salt.Length);

                // 创建散列加密
                HashAlgorithm hasher = SHA256.Create();
                using (CryptoStream cout = new CryptoStream(fout, sma.CreateEncryptor(), CryptoStreamMode.Write),
                    chash = new CryptoStream(Stream.Null, hasher, CryptoStreamMode.Write))
                {
                    BinaryWriter bw = new BinaryWriter(cout);
                    bw.Write(lSize);

                    bw.Write(FC_TAG);

                    // 读写字节块到加密流缓冲区
                    while ((read = fin.Read(bytes, 0, bytes.Length)) != 0)
                    {
                        cout.Write(bytes, 0, read);
                        chash.Write(bytes, 0, read);
                        value += read;
                    }
                    // 关闭加密流
                    chash.Flush();
                    chash.Close();

                    // 读取散列
                    byte[] hash = hasher.Hash;

                    // 输入文件写入散列
                    cout.Write(hash, 0, hash.Length);

                    // 关闭文件流
                    cout.Flush();
                    cout.Close();
                }
            }
        }
        
        /// <summary>
        /// 解密文件
        /// </summary>
        /// <param name="inFile">待解密文件</param>
        /// <param name="outFile">解密后输出文件</param>
        /// <param name="password">解密密码</param>
        public static byte[] DecryptFile(string inFile, string password)
        {
            MemoryStream f_Stream = new MemoryStream();
            // 创建打开文件流
            using (FileStream fin = File.OpenRead(inFile))
            {
                int size = (int)fin.Length;
                byte[] bytes = new byte[BUFFER_SIZE];
                byte[] bt = new byte[BUFFER_SIZE];
                int read = -1;
                int value = 0;
                int outValue = 0;

                byte[] IV = new byte[16];
                fin.Read(IV, 0, 16);
                byte[] salt = new byte[16];
                fin.Read(salt, 0, 16);

                SymmetricAlgorithm sma = DESFileClass.CreateRijndael(password, salt);
                sma.IV = IV;

                value = 32;
                long lSize = -1;

                // 创建散列对象, 校验文件
                HashAlgorithm hasher = SHA256.Create();

                using (CryptoStream cin = new CryptoStream(fin, sma.CreateDecryptor(), CryptoStreamMode.Read),
                    chash = new CryptoStream(Stream.Null, hasher, CryptoStreamMode.Write))
                {
                    // 读取文件长度
                    BinaryReader br = new BinaryReader(cin);
                    lSize = br.ReadInt64();
                    ulong tag = br.ReadUInt64();

                    if (FC_TAG != tag)
                        throw new CryptoHelpException("文件被破坏");

                    long numReads = lSize / BUFFER_SIZE;

                    long slack = (long)lSize % BUFFER_SIZE;
                    for (int i = 0; i < numReads; ++i)
                    {
                        read = cin.Read(bytes, 0, bytes.Length);
                        f_Stream.Write(bytes, 0, read);
                        chash.Write(bytes, 0, read);
                        value += read;
                        outValue += read;
                    }

                    if (slack > 0)
                    {
                        read = cin.Read(bytes, 0, (int)slack);
                        f_Stream.Write(bytes, 0, read);
                        chash.Write(bytes, 0, read);
                        value += read;
                        outValue += read;
                    }

                    bt = f_Stream.ToArray();
                    chash.Flush();
                    chash.Close();
                    byte[] curHash = hasher.Hash;

                    // 获取比较和旧的散列对象
                    byte[] oldHash = new byte[hasher.HashSize / 8];
                    read = cin.Read(oldHash, 0, oldHash.Length);
                    if ((oldHash.Length != read) || (!CheckByteArrays(oldHash, curHash)))
                        throw new CryptoHelpException("文件被破坏");
                }

                if (outValue != lSize)
                    throw new CryptoHelpException("文件大小不匹配");
                
                return bt;
            }
        }
        /// <summary>
        /// 解密文件_bk
        /// </summary>
        /// <param name="inFile">待解密文件</param>
        /// <param name="outFile">解密后输出文件</param>
        /// <param name="password">解密密码</param>
        public static void DecryptFile_bk(string inFile, string outFile, string password)
        {
            // 创建打开文件流
            using (FileStream fin = File.OpenRead(inFile), fout = File.OpenWrite(outFile))
            {
                int size = (int)fin.Length;
                byte[] bytes = new byte[BUFFER_SIZE];
                byte[] bt= new byte[BUFFER_SIZE];
                int read = -1;
                int value = 0;
                int outValue = 0;

                byte[] IV = new byte[16];
                fin.Read(IV, 0, 16);
                byte[] salt = new byte[16];
                fin.Read(salt, 0, 16);

                SymmetricAlgorithm sma = DESFileClass.CreateRijndael(password, salt);
                sma.IV = IV;

                value = 32;
                long lSize = -1;

                // 创建散列对象, 校验文件
                HashAlgorithm hasher = SHA256.Create();

                using (CryptoStream cin = new CryptoStream(fin, sma.CreateDecryptor(), CryptoStreamMode.Read),
                    chash = new CryptoStream(Stream.Null, hasher, CryptoStreamMode.Write))
                {
                    // 读取文件长度
                    BinaryReader br = new BinaryReader(cin);
                    lSize = br.ReadInt64();
                    ulong tag = br.ReadUInt64();

                    if (FC_TAG != tag)
                        throw new CryptoHelpException("文件被破坏");

                    long numReads = lSize / BUFFER_SIZE;

                    long slack = (long)lSize % BUFFER_SIZE;
                    for (int i = 0; i < numReads; ++i)
                    {
                        read = cin.Read(bytes, 0, bytes.Length);
                        fout.Write(bytes, 0, read);
                        chash.Write(bytes, 0, read);
                        value += read;
                        outValue += read;
                    }

                    if (slack > 0)
                    {
                        read = cin.Read(bytes, 0, (int)slack);
                        fout.Write(bytes, 0, read);
                        chash.Write(bytes, 0, read);
                        value += read;
                        outValue += read;
                    }
                    chash.Flush();
                    chash.Close();

                    fout.Flush();
                    fout.Close();

                    byte[] curHash = hasher.Hash;

                    // 获取比较和旧的散列对象
                    byte[] oldHash = new byte[hasher.HashSize / 8];
                    read = cin.Read(oldHash, 0, oldHash.Length);
                    if ((oldHash.Length != read) || (!CheckByteArrays(oldHash, curHash)))
                        throw new CryptoHelpException("文件被破坏");
                }

                if (outValue != lSize)
                    throw new CryptoHelpException("文件大小不匹配");

            }
        }


        /// <summary>
        /// 加密字节
        /// </summary>
        /// <param name="encryptKey"></param>
        /// <param name="P_byte_data"></param>
        /// <returns></returns>
        public static byte[] ToEncrypt(string encryptKey, byte[] P_byte_data)
        {
            try
            {
                byte[] P_byte_key = Encoding.Unicode.GetBytes(encryptKey);//将密钥字符串转换为字节序列
                MemoryStream P_Stream_MS = new MemoryStream(); //创建内存流对象
                CryptoStream P_CryptStream_Stream = new CryptoStream(P_Stream_MS, new DESCryptoServiceProvider().CreateEncryptor(P_byte_key, P_byte_key), CryptoStreamMode.Write);//创建加密流对象
                P_CryptStream_Stream.Write(P_byte_data, 0, P_byte_data.Length);//向加密流中写入字节序列
                P_CryptStream_Stream.FlushFinalBlock();//将数据压入基础流
                byte[] P_bt_temp = P_Stream_MS.ToArray();//从内存流中获取字节序列
                P_CryptStream_Stream.Close();//关闭加密流
                P_Stream_MS.Close();//关闭内存流
                return P_bt_temp;//方法返回加密后的byte 
            }
            catch (CryptographicException ce)
            {
                throw new Exception(ce.Message);
            }
        }
        /// <summary>
        /// 解密字节
        /// </summary>
        /// <param name="encryptKey"></param>
        /// <param name="P_byte_data"></param>
        /// <returns></returns>
        public static byte[] ToDecrypt(string encryptKey, byte[] P_byte_data)
        {
            try
            {
                byte[] P_byte_key = Encoding.Unicode.GetBytes(encryptKey); //将密钥字符串转换为字节序列
                MemoryStream P_Stream_MS = new MemoryStream(P_byte_data);//创建内存流对象并写入数据
                CryptoStream P_CryptStream_Stream = new CryptoStream(P_Stream_MS, new DESCryptoServiceProvider().CreateDecryptor(P_byte_key, P_byte_key), CryptoStreamMode.Read);//创建加密流对象

                byte[] P_bt_temp = new byte[200];//创建字节序列对象
                MemoryStream P_MemoryStream_temp = new MemoryStream();//创建内存流对象

                int i = 0;//创建记数器
                while ((i = P_CryptStream_Stream.Read(P_bt_temp, 0, P_bt_temp.Length)) > 0)//使用while循环得到解密数据 
                {
                    P_MemoryStream_temp.Write(P_bt_temp, 0, i);//将解密后的数据放入内存流

                }
                return P_MemoryStream_temp.ToArray();//方法返回解密后的byte

            }
            catch (CryptographicException ce)
            {
                throw new Exception(ce.Message);
            }
        }

        /// <summary>
        ///将 Stream 转成 byte[]
        /// </summary>
        /// <param name="stream"></param>
        /// <returns></returns>
        public static byte[] StreamToBytes(Stream stream)
        {
            byte[] bytes = new byte[stream.Length];
            stream.Read(bytes, 0, bytes.Length);
            // 设置当前流的位置为流的开始
            stream.Seek(0, SeekOrigin.Begin);
            return bytes;
        }


        /// <summary>
        /// 将 byte[] 转成 Stream
        /// </summary>
        /// <param name="bytes"></param>
        /// <returns></returns>
        public static Stream BytesToStream(byte[] bytes)
        {
            Stream stream = new MemoryStream(bytes);
            return stream;
        }

        /// <summary>
        /// 将 Stream 写入文件
        /// </summary>
        /// <param name="stream"></param>
        /// <param name="fileName"></param>
        public static void StreamToFile(Stream stream, string fileName)
        {
            // 把 Stream 转换成 byte[]
            byte[] bytes = new byte[stream.Length];
            stream.Read(bytes, 0, bytes.Length);
            // 设置当前流的位置为流的开始
            stream.Seek(0, SeekOrigin.Begin);
            // 把 byte[] 写入文件
            FileStream fs = new FileStream(fileName, FileMode.Create);
            BinaryWriter bw = new BinaryWriter(fs);
            bw.Write(bytes);
            bw.Close();
            fs.Close();
        }

    }
}


